jamesp
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Member since October 2012
Posts: 36,561
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Post by jamesp on Mar 6, 2017 7:31:58 GMT -5
I have been watching the rate of grinding with chunks of SiC grinding wheels carefully. The best size is taking the 5" diameter X 1" thick grinding wheel and breaking it into quarters. A quarter section lasts about 10 days. I use 3 quarter sections for 7 pound barrel. By the end of 10 days the slurry is very (too) thick. So thick the rocks are barely moving. So a lot of material is being removed. The quarter chunks are reduced to 1 inch balls. These chunks make coarse grind easy because there is no need to open barrel and add coarse grit every 2-3 days. The grind is fast because they are constantly shedding fresh full size 50-60 grit. Meaning there is never a time when the rocks are running with broken down grit. To accelerate the grind even quicker I am running a 1 to 1.5 pound rock in each 7 pound barrel. Draw back is accelerated wear on PVC barrels. May not be a problem with rubber barrels. Me don't care about barrel wear. Guessing barrel will last 1.5 years instead of 3 years. Just the way it is. Some one needs to figure a way of casting or fusing loose coarse SiC into chunks to take advantage of this time release method. Maybe mixing a batch of SiC with epoxy like grout and troweling the mix into Jiffy peat trays... I have used peat for a slurry thickener, it does fine. A bit of peat in a rotary will not hurt anything. 1.25" Jiffy trays for growing seedlings may make perfect molds.
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,561
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Post by jamesp on Mar 6, 2017 9:29:26 GMT -5
The 3 quarters is more than a half cup. Probably close to a half cup. But if you add a half cup 3 times/week to 7 pounds of rock you are using 1.5 cups/week.
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Post by captbob on Mar 6, 2017 9:37:34 GMT -5
But if you add a half cup 3 times/week to 7 pounds of rock you are using 1.5 cups/week. You come up with that all by yourself?
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Post by captbob on Mar 6, 2017 9:43:29 GMT -5
More seriously, I enjoy this SiC wheel experimentation, but this isn't the kinda thing (used grinding wheels) many of us have on hand or can easily find.
Most of us may have some old 100 grit wheels laying around, but probably not in quantity and even more doubtful to have wheels coarser than that.
You teaching us how to make the homemade SiC chunks may earn our undying affection admiration gratitude.
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Post by HankRocks on Mar 6, 2017 10:07:57 GMT -5
You may consider some sort of heat activated(baked) resin if you can find an inexpensive one. You do have the oven so heat won't be an issue. Molds will be the issue, maybe the small muffin tins, if you can stay below 450F. Then how do you keep the silicon muffins from sticking to the tin. The cast iron cornbread molds that might be a bit large but melting the mold should not be an issue. Still have the sticking issue. Of course maybe the baked silicon resin cornbread sticks would not stick to the cast iron.
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Post by captbob on Mar 6, 2017 10:27:02 GMT -5
If one could make glass that might be the ticket.
Saturate the melted glass with the SiC
Glass bonded SiC cubes (whatever shape) would not add anything to the tumble that might not be desirable such as epoxies, resins or other bonding agents.
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Post by HankRocks on Mar 6, 2017 10:39:51 GMT -5
I suspect the resin/epoxy is probably not too much a factor as that's what bonds the broken grinding wheels. It probably adds to the slurry.
The expense of whatever you use to bond might be prohibitive.
Glass might give up the SiC particles too quickly.
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,561
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Post by jamesp on Mar 6, 2017 11:03:00 GMT -5
captbob I have used up three 5 gallon buckets of those wheels. Got like 1.5 buckets left, starting to fret. Addicted to those wheels. I add loose SiC 30 too. But if away the fresh grit keeps on coming. You might be able to throw the SiC and epoxy in an old pot and heat it all to say 250F. Epoxy gets much more watery at elevated temps. Heck HankRocks, I would cast them in peat pots or cardboard egg trays. The peat pots are easy to screed level. You said the used to use pressure. If you could vibrate it down and get rid of the voids...may not be necessary. I bought a pint of el cheapo epoxy. May give the hot epoxy a go.
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